Obsidian Sync: rename duplicates; portions of text duplicated

I start having duplicates via Sync of 2 different kinds

  1. I renamed 2 folders, it seemed to work, but when syncing my other computer, both the old and the new folder showed up.
  2. I start seeing duplicate parts of notes

The sync log only has today’s info, with no details about these folders.
Sync history does not show the renames.
I don’t believe that plugins are at fault here, but it’s the Tasks plugin that made me aware of the problem (since tasks appeared twice).

Other than being more attentive, how can troubleshoot this issue more in detail?